Quote Originally Posted by Drysdan View Post
Nothing but a greataxe? At all?

Yeah,
Step 1: Fly.
Step 2: Literally anything you want, since he can no longer reach you, at all. Lots of good suggestions already, but once you're impervious to anything he does, you could literally kill him with cantrips.
This is what I was going to say. Once you are airborne, there is nothing he can do without a ranged weapon.